gistfile1.js

/* Recursively compose an arbitrarily long list of functions into a single function. */
function compose() {
  /* One function, nothing to compose. */
  if(arguments.length == 1)
    return arguments[0];
  else {
    /* Compose the head with the immediate successor. */
    var args = arguments;
    /* The composition: f(g(x)) */
    var f = [function() {
      return args[1].apply(null, [args[0].apply(null, arguments)]);
    }];
    /* If we haven't composed all, use the new composition as the head for the next. */
    return compose.apply(null, arguments.length == 2
      ? f : f.concat(Array.prototype.slice.apply(arguments, [2])));
  }
}

/* Examples */

var composed = compose(
  function(i) {
    return "is " + i;
  },
  function(j) {
    return "name " + j;
  },
  function(i) {
    return "my " + i;
  }
)
alert(composed("Chris"));
/* Yields "my name is Chris" */
/* Call stack: ("my " + ("name " + ("is " + ("Chris")))) */

composed = compose(
  function(i) {
    return i * 4;
  },
  function(j) {
    return j / 2;
  },
  function(i) {
    return i + 1;
  }
)
alert(composed(1));
/* Yields 3 */
/* Call stack: ((((1) * 4) / 2) + 1) */